I painted mine a couple months back. Painted them with the red G2 caliper paint and kept the calipers on the rotors. Jacked the car up on jack stands and cleaned the calipers with brake cleaner, sanded with 220 sand paper just to rough up the surface and then cleaned them again with the brake cleaner. Take your time cleaning the calipers because that's the most important part. When you think they are ready to start painting just clean them one more time for good measure lol.
I found the best way to mask the area was with cheap aluminum foil. You can mold the foil exactly where you want it and then use some blue painting tape to keep the foil in place. Mask the entire wheel well and then spend the money and get the preval paint sprayer. The paint sprayer really helps the finish look good in my opinion vs trying to paint with a brush and getting unwanted runs in the paint. My first coats were very light coats and I gradually increased the amount for each coat.
P.S. Buy two preval paint sprayers ($15 per sprayer) I ended up running out of the CO2 in the first sprayer half way through and ended up having to buy a new paint kit to finish the final coats because the paint only had about 4 hrs working time after you mix the reactor.
I've attached some pictures so you can see the before and after. I think it looks pretty good. The brembo decals were like $8 off eBay. Just look for high temp brembo decals. Hope this helps for other members looking to change their caliper colors for super cheap.